The invention relates to the field of oncology. More specifically, the invention relates to a method for typing colorectal cancer cells. The invention provides means and methods for differentiating colorectal cancer cells with a low metastasizing potential and with a high metastatic potential.
Worldwide over a million new cases of colorectal cancer were diagnosed in 2002, accounting for more than 9% of all new cancer cases (Ries et al., editors. National Cancer Institute Bethesda, Md. 2006. May 3, 2006. SEER Cancer Statistics Review, 1975-2003). Colorectal cancer is the third most common cancer worldwide after lung and breast with two-thirds of all colorectal cancers occurring in the more developed regions. As with all cancers, chances of survival are good for patients when the cancer is detected in an early stage. Stage I patients have a survival rate of ˜93% while the 5-year survival rate drops to ˜80% in stage II patients and to 60% in stage III patients (Sobrero et al., 2006. The Lancet Oncology 7(6): 515-517).
Despite numerous clinical trials, the benefit of adjuvant chemotherapy for stage II colon cancer patients is still debatable (Andre et al., 2006. Annals of Surgical Oncology 13(6): 887-898). Several analyses and meta-analyses have been performed of clinical trials comparing adjuvant therapy with observation in patients with stage II colon or colorectal cancer (for review, see Benson et al., 2004. Journal of Clinical Oncology 22: 3408-3419). Three-fourth of patients is cured by surgery alone and therefore, less than 25% of patients would benefit from additional chemotherapy. As a result, the number of patients receiving adjuvant chemotherapy varies significantly amongst developed countries and the official guidelines give no clear recommendation (Van Cutsem et al., 2005. Annals of Oncology 16 (suppl—1):i18-i19). For stage III patients, adjuvant treatment is recommended for all patients (Gill et al., 2004. Journal of Clinical Oncology 22: 1797-1806) although patients with T1 or T2 N1 MO tumors (stage IIIA) have a significantly better survival rate than stage II B patients indicating that many patients would not require additional chemotherapy.
The identification of the sub-group of patients that are more likely to suffer from a recurrent disease would therefore allow the identification of patients who are more likely to benefit from adjuvant treatment after surgery. Much effort has been put on the identification of clinico-pathological parameters that predict prognosis. The most important factors for predicting the risk of recurrence are emergency presentation, poorly differentiated tumor (histological grade) and depth of tumor invasion and adjacent organ involvement (T4) (Van Cutsem et al., 2005. Annals of Oncology 16 (suppl—1):i18-i19; Le Voyer et al., 2003. Journal of Clinical Oncology 21: 2912-2919). Assessment of an inadequate number of lymph node is an additional risk factor as low numbers of examined lymph nodes is associated with a decreased 5-year survival rate. Although these clinical parameters have been shown to correlate to outcome, physicians acknowledge that they are insufficient to correctly identify high risk patients.
Current pathological prediction factors are not sufficient to identify “high risk” patients, who have an increased risk for recurrent disease. It is therefore an object of the present invention to provide methods and means to allow typing of cancer samples from patients suffering from colorectal cancer to identify said high risk patients and low risk patients.